This invention relates to a track fastener apparatus of the type used to anchor seats or cargo to tracks fitted to the floor of a vehicle. The particular embodiment disclosed herein is of a track fastener apparatus for securing an aircraft passenger seating unit to the floor of a DC-10 aircraft.
Many aircraft require the capability to be differently configured to meet varying cargo and/or passenger-carrying requirements such as the removal or additional of passenger seats and/or cargo. In addition, aircraft also must have the capability of easily and quickly relocating or reposition seats and/or cargo. It is often necessary in aircraft to change the spacing between seats to increase or decrease the passenger density throughout a portion of or the entire aircraft. For example, it may be necessary to change the density of loading of a particular aircraft from its normal first class and coach density to an all-coach configuration such as might be necessary with charter operations. In addition, some aircraft, particularly those operating on late night schedules, to carry both passengers and cargo, the cargo being carried in one or more compartments normally used to carry passengers. In particular, some large aircraft frequently fly a configuration wherein passengers occupy the fore and midsection compartments, with cargo being carried in the aft compartment.
To provide this capability the manufacturers of aircraft install locking tracks that run fore and aft along the floor of the major compartments of the aircraft. These locking tracks have a slot that runs the entire length of the track along its top side. Enlarged cut-out openings are spaced at regular intervals along the length of the track to receive portions of various types of track fasteners to permit the track fasteners to be positioned along and locked into the track in order to secure passenger seats and/or cargo which is itself secured to the track fastener. These track fasteners are adjustable within the track thereby permitting the seats and/or cargo to be repositioned or removed.
The tracks and track fasteners are designed with safety as a paramount concern. A seat or cargo container which is not securely locked into the track is subject to sudden movement which can cause injury, structural damage to the aircraft or a substantial change in aircraft balance. The track assembly must be able to safely distribute the load to the track so that an unsafe load is not transmitted through only a few load distribution points in a manner that would cause an unsafe condition. It is also desireable for any track fastener to provide an indication of when the track fastener is properly locked to the track so that during inspection it can be readily determined whether the track fastener is properly tightened. Any track fastener should also be capable of being easily installed on and removed from the locking track so the seats and/or cargo can be repositioned or removed quickly, safely and with minimal effort.
Attempts have been made in the past to provide the features mentioned above. For example, U.S. Pat. No. 3,847,344 discloses an apparatus for indicating when the track fastener is properly locked in the track. This is accomplished by use of a locking wire that can be pivoted into position after the fastener has been placed in the locked position. However, the locking track fastener requires a separate distinct step in order to properly position the locking wire, and, in addition, the locking wire may be rotated into its partially locked position and thereby incorrectly indicate to an observer that the locking fastener is in its locked position when in fact it is not. In addition, the track fastener disclosed in the '344 Patent has components that engage the track and do not permit the track fastener to be readily moved lengthwise along the track since these portions must be removed from the enlarged areas of the track.
U.S. Pat. No. 4,230,432 discloses a track fastener in which a locking screw member is positioned in the housing of the track fastener in such a manner that when the track fastener is unlocked, the locking screw member extends above the top side of the track fastener and is therefore clearly visible. However, it is possible to tighten the locking wedge against the top of the track in such a way the locking screw member does not extend above the top side of the track fastener to the same extent. The seat may seem to be securely fastened to the track, but in fact the seat will come loose quite easily upon even light stress being placed on the seat or track fastener. A cursory inspection, particularly in bad lighting conditions, might lead an inspector to incorrectly conclude that the track fastener is properly locked when in fact is it not.
The invention of the present application provides a considerable additional measure of safety by making it impossible for the locking wedge of the track fastener to be tightened to any extent unless the locking wedge is properly aligned and positioned in the enlarged opening of the track for which it is intended.
DC-10 aircraft utilize a unique form of seating track which includes a relatively deep channel which permits electrical cable and wiring to be carried along the length of the aircraft in this channel. The depth of the channel is sufficiently great that under stress of the type which might be experienced during an accident the passenger seat can apply sufficient torque to the track fastener to cause it to spread and deform the channel walls. In this condition the track fitting can detach, causing the seat to wrench loose from the track.